Many different types of manually removable bottle caps have been known heretofore. Such caps include tear tabs of various designs, as well as sealing elements bonded to the undersurface of the top of the cap. In general, however, removal of these prior types of tear-off bottle caps results in tearing or damaging of the sealing element. Thus, such caps permanently lose utility after the initial tearing, and therefore are not reusable.
It is well recognized that the tear tab serves as a lever arm so that during the tearing operation, forces tending to pull the cap from the bottle are exerted along the top surface of the cap. In the early stages of the tearing operation, the skirt grips the bottle so that the force exerted by the tear tab acts to tear the cap along the score lines. As the cap is torn, however, the grip of the skirt on the bottle is relaxed. When the grip of the skirt is relaxed enough, the cap is lifted from the bottle neck.
In the prior bottle caps, where the sealing material is bonded to the cap, the seal must be broken to permit release of the cap. Accordingly, such prior caps may not be reused since the broken seal would not retain even a dust free closure.
The few bottle caps utilized heretofore which do have a capability of being reused, generally employ a detachable seal element which is held against the bottle opening by the cap. When the cap is torn off, the seal element must be retained and separately placed over the bottle opening prior to reuse of the cap. This aspect of these prior caps complicates their use and frequently increases their cost.